Circuit closer for high-low alarms



Dec- 11, D. R. YARNALL ET AL CIRCUIT CLOSER FOR HIGH-LOW ALARMS FiledJune 20, 1947 5 Sheets-Sheet 1 I INVENTOR6 1953 D. R. YARNALL ET ALCIRCUIT CLOSER FOR HIGH-LOW ALARMS 5 Sheets-Sheet 2 Filed June 20, 1947INVENTORS 5; @2706? Dec. 11, .1951 D Y RN E 2,578,276

CIRCUIT CLOSER FOR'HIGH-LOW ALARMS Filed June 20, 1947 5 Sheets-Sheet 3A TTORNEYfi 1951 D. R. YARNALL ETAL 72,573,276

CIRCUIT CLOSER FOR HIGH-LOW ALARMS Filed June 20, 1947 5 Sheets-Sheet 4jig le log INVENTORS Dec. 11, 1951 D. R. YARNALL ET AL 2,578,275

CIRCUIT CLOSER FOR HIGH-LOW ALARMS Filed June 20, 1947 5 Sheets-Sheet 5INVENTORS Patented Dec. 11, 1951 UNITED STATES PATENT .O.ZFF-.I.CIE

CIRCUIT CLOSEREOR HIGH-LOWALARMS David *Robert arnall, Philadelphia, andJames --W. Williams,- .31 d,-Ambler, Pa., assignors' toYarznallewaringtflomnany, Philadelphia,iPa., a cor- .pora innefsBennsylv nia Application'June' 20, 1947, Serial N 0.1553980 'zzflla ml Our invention relates to high-low alarms of the typeused-onboilersancl the like, to=circuit closers therefor, -and' to processes ofcircuit closmg.

A purpose of ourinventionis to reducethe reaction on a primaryindicatorshaft-of .ahighlow alarm carrying a circuit closing magnet due 'tooperation of asensitive magnetic. switch.

A further purpose is to build uptheiclosing *force exerted by the magneton the magnetic switch very gradually, obtaining smooth -,:opera- 'tionand gradual development of a slightreaction on the primary indicator.

A further purpose is to close a sensitivemag- :neticswitchby-abar=magnet, one pole of which is maintained remote from the switch:and the other pole of which :is swung close' toithe switch, so thatthepercentage change in reluctancemi' the magnetic path with unitmovement of the proximate pole will be: slight.

A further purpose is tolextendttheabarmagnet transverse totthe' axis ofthe :supportingiprimary indicator shaft, preferably equally '-inopposite directions to balance the magnetpand preferably also-to curvethe poles about the. axis.

A further purpose is to employ widezbarznagnet poles, extendingpreferably. over. morer-thanBO degrees :of arcand preferably lessIthflllZBO-LGG- grees of arc; the most :desirable span ebeing .ap-

proximately 45 degrees .of arc, .softhat 'thegeffect of the magneticfield --will' be; gra'duallyiapplied.

Aiurther purpose is to-support magneticisensi- -tive switches preferablytwo :in number, .on; adjustment arms individual to each switch, ;.and

preferably pivoted on an adjustment pivot i-in prolongation of :theprimary indicatoraxis, so that the switches can be swung aroundithearcuate .path' of movement of the "poles.

Further purposes appear in the specification and in the claims.

'Inthe drawings wethave chosen to illustrate a few only oftheembodiments which our .invention may appear, choosing the forms::shown from the standpoints .of iconvenience intilluswtration, clarity:in explanation and :satisfactory aoperation.

.Figure 1' is vafront'elevation of thezcircuit closer of; our invention.

Figure .2 is a sideelevation of the circuitjcloser.

'Figures 3 and '4 are detail diagrammatic front --elevations showingtheswitches-in diflferentad- ..justment positions.

Figure.Sisaperspective of the primary inclicator .shaft and circuitclosing magnet.

.FIE'igure 6 is a perspectivev similar to :Iigure ashowinglavariation-in the, magnet.

Figure 7 is a iront elevation partly in central longitudinal section, ofone --'form' of sensitive magnetic switch.

Figure 8 is a right side elevation ofcliigure 7 partly in central 1longitudinal section.

Figures 7a. and-8 are views corresponding to Figures 7 and 8respectively showing \a .variant iorm of :magnetic switch.

Figure 9 I is. a diagram: ofthe .alarmcircuits.

Figure "10 is: a central vertical section .through I 1 one viorm ofvprimary indicator.

sboiler.

Figure :l-iis .a diagrammatic central. ,ryertical section :of a variant:primary iindicator.

' Like numerals :refer to .like .parts throughout. v.In the. operation;of boilers. .and.other=pressure vessels, it is=c0mn11on-to:.employ.s.o.called ihighlow alarms .to :warn the .operator. gofremergencyconditionsregarding liquid llevel. :.;-Many. .of :the

most satisfactory primary;indicatorsgwhichmove a shaft at a point ofindicationinresponseto "liquid level .cr zthezlike, are.capablerofexerting very .little .force .on the, primary, indicator. shaft withoutl ss in: 1 130310 reliabi ty of th .in-

dication. This is :true -for. example of the ,mag

netizable spiral as; described; and claimed ini-fthe Un d :St t smat tapplica ns ,o ,-.llia g- J- .I, Iin. 'na S ri l-No. 5,177 24 le i .l nnryqfi,

1944, ew Pat nt No-2.50&.644 ,M@i2;30, 1.95. ni0 D n ia Bressure au e. a.e. i 1 0- 7l3.03 file -Nor b rl a 46 ..fo Me e :"Ih

:us eu ie ineswitc s i hi he se m a e e o t 1 w uit v fo e eratie sbythe m te fec iv p imar -ind cat r We h i estigate h i ssi il ao $16,111-

closing, using the well-known horseshoemagnets- Wefin theti he w tch gls i nt stantial reaction on thefprimary in icator.

. h co se. o ouri v sti t fdn f e.-@nr9 avoid substantial reaction ontheprimary I indicator andeliminate 'abruptness in, actionlug-litedesigning the mechanism.

W fin t at it .isvery;impo en it remp ey. a bar magnet, in whichthepoles are divergingand remote, rather than a horseshoemagnet,inopereti alo athe maenet ty e sw t .iQneipg only of the bar magnet,mounted on the primary indicator shaft, is brought close to a magneticswitch while the other pole is remote so that the change in thereluctance of the magnetic path due to the presence of the armature ofthe magnetic switchis gradual, and, for a given unit of magnetic motion,represents only a fraction of the change which occurs in a horseshoemagnet, with its short return path. Thus the reaction on the shaft ofthe primary indicator is much reduced, and the indicator does not jumpor deflect and low liquid level as later explained. The

shaft supports an indicator pointer 22 and on one end, transverse to theaxis, supports a bar magnet 23 of any suitable permanent magnet 25preferably curved as shown on an are about the shaft axis, and suitablyfiat in the axial direction. The poles extend for a substantial distancearound the circumference, preferably from .alloy. The bar magnet hasdiverging poles 24,

30 to 90 degrees of arc, and most desirably about 45 degrees.

It will be understood that the bar magnet is preferably not straight,but the midlines of the poles make an angle 26 which is between 45 and315 degrees, and preferably of the order of 90 to 120 degrees. In thepreferred form (Figures 1 to 5 inclusive) there is thus a recess 21 atone'side in line with the axis, and the magnet is mounted on the shaft20 by a U-clip 28 and a screw 29 passing through holes in the arms ofthe clip into the end of the shaft. in the alternate form of Figure 6,the bar magnet 23 is bored at 29' to receive the screw 29.

Arranged at adjustable positions around the magnet 23 are sensitivemagnetic switches 36 and 3|, desirably of the hermetically sealed type,held by clips 32 on arms 33 and 34 pivoted at 35 on the axis of shaft 20in prolongation of the shaft. The adjustment pivot is supported on abase plate 36 mounted on the housing 31. the clip 32 is mounted on aportion 38 beyond the pivot 35 from an adjustment extension 39 whichrides over a scale 40 under-a clamp guide 4| and is limited in travel byscrews 42. On arm 34 the On arm 33 adjustment extension 43 under guide4| is on the' same side of the pivot as the clip-supporting portion 44.Adjustment extensions 39 and 43 are recessed at 45 and permit movementhalf-way up or down on scale 40.

By swinging the adjustment extensions to dif-'*- ferent positions, theswitches 30 and 3| respectively operating on low and high liquid level,are moved to positions corresponding to different liquid levels, asshown in Figures 3 and 4. Figure 3 corresponds to a relatively lowhigh-level alarm position and a relatively high low-level alarmposition, while Figure 4 corresponds to a relatively high high-levelalarm position and a relatively low low-level alarm position. Of

course the arms 33 and 34 can be adjusted independently when screws 42are loosened, and

4 will stay in adjusted position due to the clamping action of bar 4|when screws 42 are tightened.

Figures 7 and 8 show the construction of the magnetic mercury switches,which represent one of the types of sensitive magnetic switches wellsuited to the present invention. These comprise casings 46 of glass orother insulation sealed and containing inert gas on the interior at 41.A cavity at the bottom holds a mercury pool 48, connected by a lead 49to a terminal 50 passing through the casing. The opposite terminal 5|,passing through the casing, supports an electrically conducting spiralspring 52 at its center from the outer end of which extends downward amovable contact 53, offset at .54, and having a contact end which inopen position (solid lines in Figure 7) is above and to one side of themercury pool 48 and in closed position (dot-and-dash lines in Figure 7enters the mercury pool 48. A magnetically susceptible armature 56 onthe movable contact 53 near the side wall of the cas-.

ing, moves between the positions shown in Figure 7 to close the switch(dot-and-dash position) against the action of the spring. A support 51on the terminal 5| carries an eye 58 which guides the offset portion 54of the movable contact 53.

Figures '7 and 8 show a hermetically sealed inert gas filled sensitivemagnetic switch, which employs a fixed solid metallic contact 48connected to the terminal similarly to the connection of the mercurypool in Figures 7 and 8, and cooperating With a relatively movable solidmetallic contact 55 supported on the spiral spring 52 already described.A magnetizable armature 56 is positioned on the movable element. Anextension 54' from the movable element is guided in motion by the eye58, already described.

It will thus be evident that as the magnet pole approaches the armature56 of one of the switches, force is gradually built up by the magnet onthe armature against the spring, until the switch closes.

The operation of the primary indicator is not itself part of the presentinvention, but may conform to Walter J. Kinderman United States patentapplications Serial No. 517,242, filed January 6, 1944, supra forDifferential Pressure Gauge, and Serial No. 713,035, filed November 29,1946, supra for Meter. In these devices angular motion from a primaryindicator shaft is transmitted without substantial frictional loss froma closed space in response to pressure differential or the like withinthe space.

A housing 66 of the indicator, as best seen in Figures 10 and 11,comprises a body 6| and a cover 62 united by bolts 63 and sealed byannular packing 64 on opposite sides of a diaphragm support 65 aperturedat 66. The diaphragm support is recessed at 6'! on the side toward thebody 6| in order to permit a well, later to be described, to fit into.the recess. The housing is mounted in any suitable position, such asvertical, by a bolt entering a threaded opening 68. On the side towardthe cover, the diaphragm support is recessed at 69 to permit collapseinto this space of an annular transversely free flexible diaphragmportion 16 of a diaphragm. The diaphragm is held at its upper edge bythe packing 64 which protects against leakage between the support andthe cover. At the center the diaphragm is stiffened by diaphragm plates12 which are united by threaded members '13, 14 recessed at 15 toreceive a thrust pin 76 engaging in a conical socket H and extendingthrough an opening 18 in the threaded member 1.4. The, pin I6. carries acollar I9 to prevent accidental removal of its end from the space I5.

The diaphragm H is subjected to differential pressures on opposite sidesthrough nipples 80 and 8|. The pressure upon thev inner face at, 8| is astandard pressure in liquid level devices, which should be equal to orgreater than the pressure obtained due to the highestv level of liquidindicated.

At the opposite end the thrust pin I6 engages Within a cavity ,82 of athimble 8:3 which is mounted as by peening at 84 on a leaf spring 85.The spring provides. a convenient support for an indicator horseshoemagnet 86, and retards the movement of the magnet. The horseshoe magnet86 is conveniently mounted on the spring by extending a plate 81 overthe magnet and thimble and bolting through the plate, magnet and springat 88. The thimble may conveniently be peened over at 89 to unite to theplate.

The motion of the magnet is transmitted to, the primary indicator shaft23 through a pressure wall or well 98 of suitable nonmagnetic material,which surrounds a magnetically susceptible rotatable armature 9| ofspiral formation which is external of the housing 60 in the sense thatit is not subjected to the pressure of the housing. The magnetictransmission is based upon the change of reluctance of the magnetic pathwith movement of the magnet at right angles to its .flux along the axisof the armature, accompanied by rotary reaction of the armatureto themagnet movement to reestablish the reluctance of the magnetic circuit ata balance position.

The magnet 86 is preferably a permanent magnet of highly magnetic alloyhavin curved poles 92, 93 which effectively surrounds the well 90, withsuitable clearance to permit movement longitudinally of the well.

Both the permanent magnet 23 and the permanent magnet 86 may suitably bemade of Alnico (24 to 30% nickel, 9 to 13% aluminum, balance iron) aswell known in the art.

The well is threaded at 94 into the housing and internally threaded at95 to receive the mounting of one bearing 2|, the opposite. bearing 2|being in the end of the well.

The armature 9i, like the armature. 56, may preferably be of soft ironor long carbon steel, such as Swedish iron or "core iron. Silicon bronzeis satisfactory for the well. The relation of the spiral pitch tothemagnet thickness should be relatively high. A 4 to 1* ratio givesgood results, and a 3 to 1 ratio is acceptable.

Provision is made for adjustment of the fulcrum of spring 85. Movementof the fulcrum edge normal to the plane of the spring controls the zerosetting, while movement of the fulcrum edge along the surface of thespring parallel to the spring length changes theunsupported springlength and, therefore, changes the deflection characteristics. This isequivalent to calibration for range of liquid level travel.

The spring is desirably supported at its rear end between a transverseblock 96 and its cap 31, both held together by bolts 98. If thesupporting spring were of the same thickness and width throughout itslength, the possible adjustment in range of movement due to fulcrumadjustment would be relatively small. To increase the effect of changein fulcrum, the spring can be varied in thickness or, as is moreconvenient in production, can be varied in width where it is: bent. Thespring is, accordingly made wide and is slotted at 99 adjacent the.supporting end I00, and, the walls adjacent the bifurcationqare taperedoppositely at to.- The outer walls are tapered inwardly and upwardlytoward the upper end at I02.

Although the spring is at all times supported by the block and the cap,the effective length of the spring, is determined by an adjustablefulcrum in the form of a bar I03 having a knife edge I04 extendingacross the spring. The bar I03 is movable transversely of the length ofthe knife edge. The bar I33 is slotted transversely at I05 from the backso as to permit it to he slid from the left in Figure 10 upon a barrelI06 of a spool IBI having flanges I08. The spool is rigid with a screwI09 threaded into the housingv 6B and into the block 96. The screw isaccessible for turning through an opening I I0 closed by a closure boltIII. A disc H2 on the screw I I3 mounted in the housing behind bar H13moves the bar to the left or right in Figure 10 and correspondinglymoves the fulcrum. Access to the screw I I3 is provided through anopening I I4 closed by a closure bolt I I5. Since the setting of thezero point of the indicator is dependent upon the position of the magnetto the right or left in Figure 10, the zero point can be adjusted byadvancing or retracting the disc II2. A set screw II6 prevents loweringof the bar I33 beyond the limit of adjustment.

In operation, the device of Figures 10 to 12 is controlled by motion ofthe diaphragm under differential pressure which causes the pin 16 tomove the horseshoe magnet 86 against the retardation of the spring 85.Movement of the horseshoe magnet surrounding the well causes thearmature BI to rotate and thus turn the primary indicator shaft 20.

In Figure 13 the mechanism is shown applied to a steam drum and watercolumn by which water level differences are indicated by difference inpressure on the indicator. The steam drum (boiler) II! is connected bypipes H8, H9, one reliably above and one below the water level. with thewater column I20 from which pipes I2I, I22, again one reliably above andone reliably below the water level, connect with pressure pots I23, I24.From these pressure pots pipes I25, I26 lead through valves I21 toopposite, sides of the diaphragm "II as shown in Figure 10.

In this form the pipe connection I26 carrying varying pressurecommunicates with the nipple 80 at the left hand side of Figure 10. Thepipe I25 communicates with the nipple 8I on the opposite side of thediaphragm in Figure 10. As the variant water level communicating withthe lower pressure pot I24 drops, the pressure difference with respectto the constant level in pressure pot I23 increases and the magnet isshifted along the well toward the pointer, that is, outward along thearmature, so as to give progressively lower indication for variant waterlevel.

In Figure 14 the invention is applied to a plain float I28 within aboiler or other chamber under pressure but with indication outside. Thefloat follows the level I29 of the liquid I30. The float arm or rod I 3Iis rigidly fastened to a magnet 86 so that each forms one arm of a crankpivoted at I32. The magnet thus swings angularly to the same extent asthe float arm or rod. The compartment I 33 is formed conveniently by afitting I34 attached by flanges I35 and bolts I36 to a side of theboiler I31. The compartment communicates with the boiler through acasing opening I38. The magnet can be of the same character as magnet 86except that for a considerable angle of swing of the magnet the polesdesirably are opposite parallel surfaces. The well 90 and the armature91 may be as in Figures and 11.

It will be evident that the advantages of the invention in minimizingreaction on the primary indicator shaft from the magnetic mercuryswitches and obtaining smooth action, can be obtained with any of a widevariety of alarm circuits. For example, in Figure 9 we illustrate a lowlevel alarm I39 such as an electric bell or lamp, in circuit with switch30 across electric power lines I40. Similarly a high level alarm I4! isin circuit with a switch 31 across the lines I40. Other suitable alarmcircuits may be used.

In view of our invention and disclosure variations and modifications tomeet individual whim or particular need will doubtless become evident toothers skilled in the art, to obtain all or part of the benefits of ourinvention without copying the structure shown, and we, therefore, claimall such insofar as they fall within the reasonable spirit and scope ofour claims.

Having thus described our invention what we claim as new and desire tosecure by Letters Patent is:

1. In a liquid indicator, a primary indicator including a shaft turningin response to high and low quantities to be indicated, a singledivergent U-shaped permanent magnet positioned centrally on the shaftwith the plane or" the U transverse to the shaft, an adjustment pivot inprolongation of the axis of the shaft, an adjustment arm on theadjustment pivot having a plurality of angular adjustment positions, aswitch mounted on the adjustment arm remote from the pivot and having arelatively fixed contact element, a swingable contact element adapted tocontact the relatively fixed contact element when the switch is closed,having a spring urging the contact elements into open position andhaving a magnetizable armature on the movable contact element located atone side of the shaft generally in prolongation of a radius of the orbitof turning of the magnet, the armature being swingable about a pointlocated on a line generally transverse to the said radius at a positionremote from the radius, and the armature adapted to be magneticallyinfluenced to move the movable contact for closing the switch, theswitch in closed position having one magnet pole adjacent the armatureand the other magnet pole remote therefrom and the magnet pole adjacentthe armature being the only magnet pole adjacent thereto.

2. In 'a liquid indicator, a primary indicator including a shaft turningin response to high and low quantities to be indicated, a singledivergent U-shaped permanent magnet centrally positioned on theshaft'with the plane of the U transverse to the shaft, the magnet havingradially outwardly directed arcuate poles each covering 30 to 90 of thearc of turning of the magnet, an adjustment pivot in prolongation of theaxis of the shaft, a'pair of adjustment arms on the adjustment pivotextending in divergent directions, switches each mounted on one of theadjustment arms remote from the pivot and each having a relatively fixedcontact element, a movable contact element adapted to contact therelatively fixed contact element when the switch is closed, a springurging the contact elements into open position, and a magnetizablearmature on the movable contact element located at one side of the shaftgenerally in prolongation of a radius of turning of the magnet andswingable about a point located on a line generally transverse to saidradius and remote therefrom, the armature being adapted to bemagnetically influenced to move the movable contact element of theswitch to close the switch, each switch in closed position having onepole adjacent the armature and the other pole remote from the armatureof the switch when closed and the pole adjacent the armature of theclosed switch being the only magnet pole adjacent such armature.

DAVID ROBERT YARNALL. JAMES W. WILLIAMS, 3RD.

REFERENCES CITED The following references are of record'in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,529,470 Dowd Mar. 10, 19252,109,953 Bates Mar. 1, 1938 2,245,596 Lindberg June 17, 1941 2,307,304Rudd Jan. 5, 1943 2,319,010 McLeod May 11, 1943 2,419,942 Brewer May 6,1947 2,459,930 Fink Jan. 25, 1949 FOREIGN PATENTS Number Country Date576,685 Germany May 12, 1933 720,957 France Dec. 12, 1931

